When analysing the data on web campagining of the EP elections of 2009, I re-analysed the data Pippa Norris was so kind to let me use. My intention was to show the need for testing on multi-dimensionality of a set of indicators. Originally I intended to include the following in the article about EP web campaigning (Vergeer, Hermans & Cunha, 2013), but this was a classic case of ‘killing your darlings’, because the article became too long.
Norris distinguished the two dimensions of Information and Communication a priori, while I wasn’t sure when reviewing the indicators. Some of the indicators didn’t seem to fit the dimensions. For instance, the search function is seen as an indication for communication, whereas this automated feature might also be included to measure informing. To see whether there is different view on the set of indicators, I performed a multiple correspondence analysis (i.e. multivariate cross tabulation (cf. Greenacre, 2007). This resulted in a different dimensional structure. The slide shows that only a small number of web features indicators compose a single dimension[i]. The remaining indicators do not show significant (co-)variance for a second dimension.

Interpreting the dimension shows us that it refers to the presence (right from the origin) and absence of specific web features (left from the origin): the more to the right the more features political parties have on their websites. The second finding is that looking at the labels C (for communication) and I (for information; cf. Norris 2001) these features are randomly scattered across the dimension. This suggests that web features that were assigned to two different dimensions should be merged according to the correspondence analysis. More close inspection also suggests that these features refer to enabling the website visitor to enlist to participate in parties’ activities.
Below the horizontal line, so-called passive variables are presented for descriptive purposes[ii]. Looking at which parties score low or high on the degree of enabling people to participate, we see that it is in particular a) the major and the minor (and not the fringe parties), b) the Green, extreme left, and conservative parties that offer these features more than average. In particular, the liberals and the center parties show below average presence of participation web features.

Notes:[i] Eigen value = 6.560, Inertia = .205, Cronbach’s α = .875.
‘C’ and ‘I’ indicate the original communication and Information functions as distinguished by Norris (2001).
Categories above the horizontal line belong to variables that influence the dimensional structure. The categories below the horizontal line are supplemental variables that do not influence the dimensionality and are merely included for descriptive purposes.[ii] Supplementary variables do not influence the dimensionality which arises on the from the analysis on web features (cf. Greenacre, 2007).